class A:
    def __init__(self):
        self.namea="aaa"

    def funca(self):
        print("function a : %s"% (self.namea))

class B(A):
    def __init__(self):
        #这一行解决了问题
        #A.__init__(self)
        super(B,self).__init__()
        self.nameb="bbb"

    def funcb(self):
        print('function b : %s' % (self.nameb))

if __name__ == '__main__':
    b=B()
    b.funcb()
    b.funca()
    print( isinstance(b,B))
    
